Baby not feeding well past two weeks

Elizabeth

Up until 2 weeks ago, my baby was having 800-850ml of expressed breastmilk plus a little bit more from nursing. I only really nurse him to sleep. I’m not 100% sure how much he gets then but I don’t think it is too much because he falls asleep and stops drinking after a couple of minutes. Recently he has been extremely fussy while taking his bottles. He used to drink 150-170ml every 3-3.5 hours (5 bottles a day). He is now taking around 100-150ml every 3.5-4 hours and sometimes only will have 4 bottles a day. This means his intake has decreased around 200-350ml for the whole day which is quite concerning for me. We haven’t been doing anything differently so I’m not sure why this is happening. If anyone has any ideas or similar experiences that would be great